A run-flat tire provided in a sidewall portion with a side-reinforcement rubber layer whose cross section is crescent-shaped has been proposed. When the inner pressure is decrease by a puncture, the side-reinforcement rubber layer supports the load of the tire, and the deflection of the tire is prevented. such run-flat tire is able to run for a relatively long distance in a punctured state (hereinafter, referred to by “run-flat running” in some situations).
During run-flat running, deformation and restoration of the side-reinforcement rubber layer occur repeatedly, and the side-reinforcement rubber layer c generates heat. If the temperature of the side-reinforcement rubber layer becomes high, breakage occurs. Accordingly, a run-flat tire in which breakages resulting from heat are hard to occur is desired.
In order to solve the above problem, there has been proposed a run-flat tire in which rubber having a high thermal conductivity is used for a side-reinforcement rubber layer. This run-flat tire is further provided in the outer surface of the sidewall portion with a large number of concavo-convex patterns (for example, undermentioned patent document 1). In such run-flat tire, a rise in the temperature of the side-reinforcement rubber layer is suppressed. As the outer surface of the sidewall portion of this run-flat tire is provided with a large surface area owing to the concavo-convex patterns, the sidewall portion is improved in the radiation performance.    Patent document 1: Japanese Patent Application Publication No. 2010-155576
However, the durability of the run-flat tire is required to be further improved.